The Intel-backed Mobile PC Extended Battery Life Working Group has published guidelines for vendors keen to create fuel cells to power portable PCs.

The document is intended to provide fuel-cell developers will details of the devices their products will have to power, whether the cells will sit inside the devices in place of regular rechargeable batteries, or operate as an alternative to an external AC adaptor. Essentially, it defines the problem the fuel cell developers have to solve.

The guidelines cover electrical, mechanical, control, thermal, environmental and regulatory aspects of fuel cells designed for notebook computers. The document can be obtained by emailing the organisation.

The Group sees the development of fuel cells for notebooks as aparticularly challenging. Batteries are well able to provide laptops with as much or as little power as they need, catering for the 'bursty' nature of notebook energy demand. Fuel cells, by contrast, were conceived to supply a continual, steady level of power.

According to the EBLWG - which sounds more like a small Welsh town than an IT industry consortium - some 60 companies around the world are working on fuel cells for mobile PCs.

Fuel cells typically use the Direct Methanol technique, in which quantities of water are methanol mixed in the presence of a catalyst causing a chemical reaction that generates a voltage between two electrodes as by-product. Connect the electrodes to a circuit and you have yourself a power source.

It is another matter to turn this concept into a device that can power a mobile phone, PDA or a notebook for a day or more: working product seems just as far away now as it did two years ago when sundry firms began making bullish claims for their fuel cell development efforts.

NEC, for example, has regularly demonstrated notebook fuel cell prototypes since 2003, originally pledging to bring such a device to market by late 2004. By the end of 2005, it said, it would have a machine on the market that could operate for 40 hours. These days, it's a little more cautious about commercial releases, and won't insay when it expects this stuff to appear.

In March this year, Nokia put its own fuel-cell development programme on hold. ®